From Wild World Wiki

Nookway is the third stage of Nook's shop. Nook will upgrade to this shop when you have traded 90000 bells with him. He will close the store for a day (he'll give you warning the day before) to upgrade, and after the day closed, the Nook'n Go will have become Nookway.

Nookway stocks a greater number of items for sale than the previous stores. On sale at the start of any day will be:

Personal tools